US20130154772A1 - Waveguide band-pass filter with pseudo-elliptic response - Google Patents
Waveguide band-pass filter with pseudo-elliptic response Download PDFInfo
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- US20130154772A1 US20130154772A1 US13/809,109 US201013809109A US2013154772A1 US 20130154772 A1 US20130154772 A1 US 20130154772A1 US 201013809109 A US201013809109 A US 201013809109A US 2013154772 A1 US2013154772 A1 US 2013154772A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
- H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/2016—Slot line filters; Fin line filters
Definitions
- the present invention refers to the field of waveguides and in particular to waveguide band-pass filters.
- Waveguide band-pass filters which comprise a cascade of waveguide segments whose length is about half of the central wavelength of the filter ( ⁇ /2) or multiples of such a value which act as resonators and are coupled to each other (and to input/output guides) by discontinuities such as, typically, diaphragm-structures. These coupling-discontinuities present an equivalent circuit having a shunt reactance.
- the reactance value usually inductive, determines the entity of the coupling between the resonating guide segments.
- U.S. Pat. No. 7,391,287 discloses a “H-plane” waveguide filter having transmission zeros.
- the article by W. Maenzel, F. Alessandri, A. Plattner, and J. Bornemann, “Planar integrated waveguide diplexer for low-loss millimeter-wave applications”, in Proc. of the 27th European Microwave Conf., Jerusalem, September 1997, pp. 676-680 illustrates the use of structures comprising rectangular guide segments placed alongside the filter body, which act as a shunt “stubs”, so as to introduce transmission zeros in the response from the guide band-pass filter.
- US-A-2009-0153272 discloses the use of resonant posts inside the band-stop filter, wherein such posts are spaced by coupling waveguide segments between the resonant posts themselves.
- the distance between the resonant posts is 3 ⁇ 4 of the central wavelength of the band-stop filter stopband.
- the problem on which the present invention is based is to provide an alternative waveguide band-pass filter in respect to those known and which, for example, allows an easy manufacturing, while offering good performances in terms of selectivity and keeping compact overall dimensions.
- FIG. 1 shows an axonometric and schematic view of the inner structure of an example of a waveguide band-pass filter
- FIG. 2 shows an equivalent electrical scheme of the band-pass filter in FIG. 1 comprising inductive reactances and reactances associated to resonant discontinuities;
- FIG. 3 a shows an example of a reduced-height post usable in said filter
- FIG. 3 b shows the equivalent electric circuit of said reduced-height post
- FIG. 4 shows behaviours of the reduced-height post reactance depending on frequency and for different values of its height
- FIG. 5 shows behaviours of the electric length of the line equivalent to such a reduced-height post depending an frequency and for different values of its height
- FIG. 6 shows behaviours of the electric length of the line equivalent to such a reduced-height post depending on frequency and for different values of its lateral dimension
- FIG. 7 shows the behaviour of the transmission coefficient S 21 and of the reflection coefficient S 11 experimentally measured on a band-pass filter analogous to that in FIG. 1 and also shows the behaviours of said coefficients obtained by means of simulation;
- FIG. 8 a shows an example of an inductive coupling device made by a full-height septum (asymmetric inductive iris);
- FIG. 8 b shows another example of an inductive coupling device made by an individual full-height post with a square base
- FIG. 8 c shows a capacitive coupling device made by a full-width septum (asymmetric capacitive iris);
- FIG. 9 a shows an example of a resonant coupling device made by an individual reduced-height post with a square base
- FIG. 9 b shows another example of resonant coupling device made by two reduced-height posts with a square base
- FIG. 10 shows an exploded view of a first embodiment of the band-pass filter of FIG. 1 which can be made by milling
- FIG. 11 shows an exploded view of a second embodiment of the band-pass filter of FIG. 1 which can be made by milling;
- FIG. 12 shows an exploded view of a third embodiment of the band-pass filter of FIG. 1 which can be made by the metal insert technique;
- FIG. 13 shows the behaviour of the transmittance S 21 and reflectance S 11 obtained by simulation relative to a band-pass filter analogous to that in FIG. 12 ;
- FIG. 14 shows the inner structure of a fourth embodiment of the band-pass filter of FIG. 1 of a dielectric type
- FIG. 15 shows the behaviour of transmittance S 21 and reflectance S 11 obtained by simulation relative to a band-pass filter analogous to that in FIG. 14 .
- FIG. 1 schematically shows the inner structure of an exemplary band-pass filter which can be implemented in a waveguide 100 .
- FIG. 2 shows the equivalent scheme 110 of the band-pass filter 100 .
- a pass-band B is associated having a central wavelength designated by ⁇ g0 .
- the band-pass filter 100 can be made, according to an example, by means of a metal rectangular waveguide of dimensions a, along an axis x, and b, along an axis y.
- the band-pass filter 100 comprises an input 3 for a signal (i.e. a radiation/electromagnetic wave) to be filtered, a first inductive discontinuity coupling device 4 , connected to input 3 , and a first waveguide 5 resonator segment, coupled to input 3 by the first coupling device 4 .
- the first inductive discontinuity coupling device 4 can be made, according to a first embodiment, by means of an iris or inductive diaphragm comprising two metal septums (also referred to by reference numerals 4 ) arranged symmetrically in respect to a median longitudinal plane, which develops parallel to an axis z of the radiation propagation.
- the metal septums 4 of the first inductive diaphragm identify a first coupling radiation opening 24 of the electromagnetic field.
- the first inductive diaphragm 4 is represented as an optimal shunt inductor having an inductive impedance jX 4 .
- the walls of the first inductive diaphragm 4 have the same height as the height b of filter 100 .
- the first resonator segment of the waveguide 5 has a length, taken on the axis z, approximately equal to half of length of the central wave of the filter: ⁇ g0 /2 and it is coupled to the input 3 by the inductive diaphragm 4 .
- the resonator segment 5 can also have a length which is multiple of the value ⁇ g0 /2.
- the first resonator segment 5 is coupled to a second resonator segment 7 by a first resonant coupling 6 .
- the first resonant coupling device is a resonant coupling structure which introduces a discontinuity configured to introduce a zero in the transmission frequency response of the band-pass filter 100 .
- the first resonant coupling device 6 is configured to resonate at a frequency equal to the value of the frequency of the zero being introduced in the transmitting response of the band-pass filter 100 .
- a transmission zero concurs to increase the selectivity of the filter in the higher and lower stop-bands of the filter 100 itself.
- the device For different frequencies from the resonance frequency of the first resonant coupling device 6 , the device itself behaves as a coupler.
- the position on the frequency axis of the transmitting zero can be determined by synthesis procedures known to those skilled in the art.
- the transmission zero corresponds, in a practical implementation of the filter 100 , to an attenuation peak.
- the first resonant coupling device 6 can be made by at least a body within the waveguide of the filter 100 and having a reduced height relative to height b of the waveguide itself.
- the first resonant coupling device 6 comprises two parallelepiped-shaped (for example, with a square base) posts, parallel oriented to axis y, arranged, for example, symmetrically relative to the median longitudinal plane and having a height h lower than dimension b.
- Such first reduced-height posts 6 are schematically depicted in FIG. 2 as a shunt-arranged resonant circuit element and therefore as a series of an inductor and a capacitor with a total reactance X 6 (with impedance jX 6 ).
- Such an impedance jX 6 results in the presence of a zero at the frequency fz 1 in the transmission response of the band-pass filter 100 .
- first reduced-height posts 6 play a role as a resonant body, they act for different frequencies from the resonance frequency as a coupling device which, in conjunction with the first diaphragm 4 , causes the first guide segment 5 to be a resonant cavity.
- the second resonator segment 7 with a length equal to approximately half of the central wavelength of the filter (i.e. ⁇ g0 /2) has an end (opposite the first posts 6 ) connected to a second inductive discontinuity coupling device 8 .
- a coupling device 8 is analogous to the first device 4 and comprises a second inductive diaphragm which identifies a second opening 9 for radiating.
- the second inductive discontinuity coupling device 8 is represented by another inductive shunt impedance jX 8 .
- the band-pass filter 100 further comprises a third resonator segment 10 with a length approximately equal to ⁇ g0 /2, coupled to the second resonator segment 7 by the second inductive diaphragm 8 .
- the third resonator segment 10 is connected to a third inductive discontinuity coupling device 11 (analogous to the first coupling device 4 ), implemented by a further inductive diaphragm (impedance jX 11 ) provided with a third aperture 12 .
- the third resonator segment 10 is further coupled to a fourth resonator segment 13 (of a length ⁇ g0 /2) connected to a second resonator coupling device 14 , comprising two second reduced-height posts, and analogous to the first coupling device 6 and having an impedance jX 14 .
- the second reduced-height posts 14 are such to resonate, for example, at a different resonance frequency f z2 and therefore they cause the presence of another zero in the transmitting frequency response of the band-pass filter 100 , at the frequency f z2 .
- the zero placed at frequency f z1 increases the selectivity in the lower stop-band
- the zero at frequency f z2 increases the selectivity of the higher stop-band at the pass-band B of the filter 100 .
- the second posts with a reduced height 14 act as a coupling device.
- the fourth resonator segment 13 is coupled to a fifth resonator segment 15 (approximately ⁇ g0 /2 long) by the second posts with a reduced height 14 .
- the fifth resonant segment 15 is then coupled to an output 17 of the filter 100 by a fourth inductive discontinuity coupling device 18 implemented by a respective fourth inductive diaphragm having a fourth opening 19 and an inductive impedance jX 18 .
- the output 17 of the filter 100 is the waveguide segment which has an output opening 25 for providing the filtered signal and for being coupled to a load or to a further waveguide segment or to a further filter.
- the resonant coupling devices 6 and 14 are arranged in respective regions of the filter 100 guide wherein the electric field has is at the minimum, in order not to degrade the figure of merit of the resonator guide segments 5 , 7 , 13 and 15 adjacent to such resonant coupling devices.
- the dimensioning of the first, second, third and fourth inductive diaphragm 4 , 8 , 11 and 18 , and the first and second reduced-height posts 6 and 14 , is such that each of these devices acts as an impedance inverter around the central frequency of the filter 100 .
- the band-pass filter 100 may comprise a number N of cavities, equal to the filter order.
- the filter 100 may comprise a plurality of resonant coupling structures in generally located (analogous to structures 6 and 14 ), in order to introduce in the band-pass response up to N+1 transmission zeros for a N-order filter.
- the frequency value f z1 of the first zero (e.g, lower than the mid-band frequency f 0 of the filter 100 ) and the frequency value f z2 of the second zero (e.g, higher than the mid-band frequency f 0 of the filter 100 ) may be suitably selected in the stop-bands within the whole operative band of the waveguide, i.e. from the cut-off frequency f c up to the value 2f c and beyond.
- FIG. 3 a shows an example of the first resonant coupling device 6 , in the case of an individual square-base, reduced-height post with a side d and a height h, arranged so that it is centred in respect to the transversal cross-section of the waveguide where it is inserted.
- FIG. 3 b shows the circuit equivalent to the first reduced-height post 6 , comprising an impedance jX 6 parallel between two segments of the transmission line having length ⁇ 6 , to which the following parameters are associated:
- Zo is, the characteristic impedance of two segments of the transmission line
- ⁇ 6 is the equivalent electric length of the two segments of transmission line
- the equivalent reactance X 6 and the electric length ⁇ 6 are related to the transmission parameters of the first reduced-height post 6 according to the following relations:
- the behaviour of the normalized reactance of the first reduced-height post 6 corresponds to a LC-series resonator around its own resonance frequency. Such a resonance frequency decreases when height h increases.
- the frequency dependence of the equivalent length ⁇ 6 is diagrammatically depicted in FIG. 5 , where both reference sections are arranged at the longitudinal symmetry plan of the first reduced-height post 6 (To in FIG. 3 a ).
- the behaviour of the equivalent electric length ⁇ 6 is analogous to the one of a full-height post having an inductive behaviour; the slope of the electric length ⁇ 6 increases upon the increase of height h.
- the resonance frequency and the behaviour of the ratio X 6 /Z 0 with the frequency depend on both the height h and on the side d. This behaviour allows to use the reduced-height post 6 as a coupler between waveguide resonators and allows also the introduction of transmission zero.
- a transmission response may be obtained by the filter which is, for example, of the Chebyshev type, with transmission zeros (pseudo-elliptical response). Due to the presence of zeros, thus the band-pass filter selectivity can be increased (i.e. the attenuation in the higher and lower stop-bands at the pass-band) with the same number of resonators.
- FIG. 7 illustrates the behaviour of transmittance S 21 and reflectance experimentally measured on a band-pass filter analogous to that in FIG. 1 , schematically depicted in FIG. 2 , implemented with a waveguide and having two transmission zeros (corresponding in the practice to attenuation peaks).
- the experiments were carried out on a filter made by the Applicant in a R70/WR137 guide, having inner dimensions equal to 34.85 mm ⁇ 15.799 mm, using silvered aluminium.
- the project was carried out according to the following specifications
- an electromagnetic wave in the form of, the mode TE 10 (basic mode in a rectangular guide) affects the input 3 .
- the electromagnetic wave propagates along the axis z of the filter 100 , being partially reflected at the input 3 and partially transmitted at the output 17 , according to the frequency of the wave itself.
- the electromagnetic wave with a frequency comprised within the pass-band B of the filter itself interacts with the resonances of the resonant segments 5 , 7 , 10 , 13 , and 15 and, due to the coupling devices 4 , 6 , 8 , 11 , 14 and 18 , it is transmitted to the output 17 with a reduced reflection at the input 3 .
- the electromagnetic wave with a frequency outside the pass-band of the filter 100 instead, undergoes reflections within the filter and therefore it is substantially stopped, to an extent which depends on the difference between the wave frequency and the filter central frequency.
- the electromagnetic wave having a frequency equal to one of the resonance frequencies of the two resonant coupling devices 6 and 14 is totally reflected at input 3 (with a null transmission at the output 17 , giving rise to an attenuation peak) as the effect of the short-circuit created along the guide by the resonant coupling devices.
- each of the inductive diaphragms described above may be made not by the pairs of symmetrical septums 4 , 8 , 11 and 18 shown in FIG. 1 , but by the following alternative modes:
- an asymmetrical inductive iris comprising an individual full-height septum 50 ( FIG. 8 a );
- a full-height inductive post 51 ( FIG. 8 b ): the post may be centred, or not, have a rectangular, circular or other base; there can be one or more full-height inductive posts 51 .
- each of the resonant coupling devices 6 and 14 may be implemented, as an alternative to the embodiment in FIG. 1 , by one or more full-height posts having different forms (for example, with a rectangular, square, circular or other base).
- FIG. 9 a shows an individual reduced-height post 53 with a square plan
- FIG. 9 b shows a pair of reduced-height posts 54 and 55 .
- the waveguide 200 of FIG. 10 can be obtained by processing an individual metal slug (corresponding to the bottom of the waveguide 200 , which comprises the bottom wall 22 ), for example, by milling steps (which can be carried out by Numeric Controlled machines) which allow, by removing the material, to form the bodies which form the inductive/capacitive or resonant discontinuities present in the waveguide 200 .
- the rounding offs within the waveguide 200 shown as a way of example in FIG. 10 , refer to the particular use of a candle-mill.
- FIG. 12 refers to another embodiment 300 of the “metal insert-type” band-pass filter 100 , which is an alternative to those of FIGS. 10 and 11 .
- the metal-insert type band-pass filter 300 is made by assembling (for example by welding or the like) a first guide shell 31 , a structure 32 and a second guide shell 33 , all made of metal.
- the first and the second guide shells 31 and 33 when assembled, form a rectangular wave guide.
- the structure 32 intended to be placed in the middle of the wave guide and parallel to the axis of propagation z comprises a carrying longitudinal top laminar rod 34 and a carrying longitudinal bottom laminar rod 35 , between which a plurality of laminar discontinuity bodies extend.
- the structure 32 comprises a first reduced-height laminar body 36 , a first full-height laminar body 37 , a second reduced-height laminar body 38 , a second full-height laminar body 39 and a third reduced-height laminar body 40 .
- the four guide segments interposed between consecutive laminar bodies 36 , 37 , 38 , 39 and 40 are segments intended to operate as resonators within the pass-band. It is to be noted that also two plates, analogous to plate 32 , may be used, each one having the plurality of discontinuities indicated above, which will be arranged, preferably, symmetrically in respect to a longitudinal middle plane of the assembled waveguide.
- the metal-insert band-pass filter 300 of FIG. 12 is a four-resonator filter with three transmission zeros.
- FIG. 13 shows the behaviours of the reflectance S 11 and the transmittance S 21 obtained by numerical simulation, referring to an example of the metal insert filter 300 of FIG. 12 with a guide dimension of 30 ⁇ 15 mm; pass-band 7.50-7.75 GHz, return losses 20 dB, three zeros at the following frequencies: 7 GHz, 8.25 GHz and 9 GHz.
- the alternating inductive coupling devices in respect to the resonant coupling devices may follow a different order from those disclosed and designated as a way of example in the accompanying Figures.
- a thin metallised dielectric plate instead of metal lamina 32 a thin metallised dielectric plate may be used, from the processing thereof the above disclosed coupling devices being obtained (“E-plane filters” technique).
- FIG. 14 refers to an embodiment 400 of the band-pass filter 100 , which may be implemented by processing the low-loss dielectric slug, and suitable for the guided propagation of electromagnetic waves, obtaining hollow geometrical shapes which reproduce as a negative both the shape of the inductive coupling devices such as the diaphragms 4 , 8 , 11 and 18 and the resonant coupling devices (such as the two posts 6 ).
- the dielectric-type filter 400 of FIG. 14 is a four-resonator band-pass filter with a transmission zero. For the sake of clarity of the depiction in FIG. 14 , they are not shown.
- FIG. 15 shows the behaviours of the reflectance S 11 and transmittance S 21 obtained by a numerical simulation with reference to an example of the dielectric filter 400 of FIG. 14 , made of quartz, of 15 ⁇ 7.5 mm; pass-band 7.5-8.00 GHz, return loss 20 dB, a zero at 8.85 GHz.
- the band-pass filter 100 and its different embodiments disclosed above, with reference to the several appended figures, may further comprise adjusting screws (not shown since they are known to those skilled in the art) which allow to carry out a fine calibration by compensating possible process tolerances.
- the band-pass filter 100 may be used in waveguides which operate at the typical microwave frequencies, for example at frequencies ranging from 100 MHz and 40 GHz.
- the disclosed band-pass filter is advantageous since it allows to obtain a remarkable increase in the selectivity in respect to the prior art filters, with the same number of resonators, and at the same time it may be implemented quite simply, with similar size and losses, and according to the different technologies currently available.
- a particular advantage is due to the possibility to implement also the resonant coupling devices by bodies within the guide itself.
Abstract
Description
- The present invention refers to the field of waveguides and in particular to waveguide band-pass filters.
- Waveguide band-pass filters are known which comprise a cascade of waveguide segments whose length is about half of the central wavelength of the filter (λ/2) or multiples of such a value which act as resonators and are coupled to each other (and to input/output guides) by discontinuities such as, typically, diaphragm-structures. These coupling-discontinuities present an equivalent circuit having a shunt reactance. The reactance value, usually inductive, determines the entity of the coupling between the resonating guide segments.
- The synthesis of such waveguide filters, called “filters with directly-coupled resonator” is analysed in G. L. Matthaei, L. Young e E. M. T. Jones, “Microwave filters, Impedance-Matching Networks, and Coupling Structures” ed. McGraw Hill, 1964.
- U.S. Pat. No. 7,391,287 discloses a “H-plane” waveguide filter having transmission zeros. The article by W. Maenzel, F. Alessandri, A. Plattner, and J. Bornemann, “Planar integrated waveguide diplexer for low-loss millimeter-wave applications”, in Proc. of the 27th European Microwave Conf., Jerusalem, September 1997, pp. 676-680 illustrates the use of structures comprising rectangular guide segments placed alongside the filter body, which act as a shunt “stubs”, so as to introduce transmission zeros in the response from the guide band-pass filter.
- US-A-2009-0153272 discloses the use of resonant posts inside the band-stop filter, wherein such posts are spaced by coupling waveguide segments between the resonant posts themselves. The distance between the resonant posts is ¾ of the central wavelength of the band-stop filter stopband.
- The applicant has noted that, with reference to the waveguide band-pass filters, the prior art does not offer any solutions which enable to achieve an increase in filter selectivity by not complex manufacturing procedures.
- The problem on which the present invention is based is to provide an alternative waveguide band-pass filter in respect to those known and which, for example, allows an easy manufacturing, while offering good performances in terms of selectivity and keeping compact overall dimensions.
- The above problem is solved by a band-pass filter as recited in the appended
claim 1 and particular embodiments thereof as defined in thedependant claims 2 to 15. - Some particular embodiments of the present invention are disclosed in detail below, as a way of example and not a limitation, with reference to the accompanying drawings, wherein:
-
FIG. 1 shows an axonometric and schematic view of the inner structure of an example of a waveguide band-pass filter; -
FIG. 2 shows an equivalent electrical scheme of the band-pass filter inFIG. 1 comprising inductive reactances and reactances associated to resonant discontinuities; -
FIG. 3 a shows an example of a reduced-height post usable in said filter; -
FIG. 3 b shows the equivalent electric circuit of said reduced-height post; -
FIG. 4 shows behaviours of the reduced-height post reactance depending on frequency and for different values of its height; -
FIG. 5 shows behaviours of the electric length of the line equivalent to such a reduced-height post depending an frequency and for different values of its height; -
FIG. 6 shows behaviours of the electric length of the line equivalent to such a reduced-height post depending on frequency and for different values of its lateral dimension; -
FIG. 7 shows the behaviour of the transmission coefficient S21 and of the reflection coefficient S11 experimentally measured on a band-pass filter analogous to that inFIG. 1 and also shows the behaviours of said coefficients obtained by means of simulation; -
FIG. 8 a shows an example of an inductive coupling device made by a full-height septum (asymmetric inductive iris); -
FIG. 8 b shows another example of an inductive coupling device made by an individual full-height post with a square base; -
FIG. 8 c shows a capacitive coupling device made by a full-width septum (asymmetric capacitive iris); -
FIG. 9 a shows an example of a resonant coupling device made by an individual reduced-height post with a square base; -
FIG. 9 b shows another example of resonant coupling device made by two reduced-height posts with a square base; -
FIG. 10 shows an exploded view of a first embodiment of the band-pass filter ofFIG. 1 which can be made by milling, -
FIG. 11 shows an exploded view of a second embodiment of the band-pass filter ofFIG. 1 which can be made by milling; -
FIG. 12 shows an exploded view of a third embodiment of the band-pass filter ofFIG. 1 which can be made by the metal insert technique; -
FIG. 13 shows the behaviour of the transmittance S21 and reflectance S11 obtained by simulation relative to a band-pass filter analogous to that inFIG. 12 ; -
FIG. 14 shows the inner structure of a fourth embodiment of the band-pass filter ofFIG. 1 of a dielectric type; -
FIG. 15 shows the behaviour of transmittance S21 and reflectance S11 obtained by simulation relative to a band-pass filter analogous to that inFIG. 14 . -
FIG. 1 schematically shows the inner structure of an exemplary band-pass filter which can be implemented in awaveguide 100.FIG. 2 shows theequivalent scheme 110 of the band-pass filter 100. To the band-pass filter 100 a pass-band B is associated having a central wavelength designated by λg0. The reciprocal band-pass filter 100 ofFIG. 1 , is of the order N=5 and has two transmission zeros. - The band-
pass filter 100 can be made, according to an example, by means of a metal rectangular waveguide of dimensions a, along an axis x, and b, along an axis y. In more detail, the band-pass filter 100 comprises aninput 3 for a signal (i.e. a radiation/electromagnetic wave) to be filtered, a first inductivediscontinuity coupling device 4, connected toinput 3, and afirst waveguide 5 resonator segment, coupled to input 3 by thefirst coupling device 4. - As it is shown in
FIG. 1 , theinput 1 is a waveguide segment having aninput opening 20 which can be coupled, for example, to a radiation source or to a circuit in a waveguide by means of a flange (components not shown). - The first inductive
discontinuity coupling device 4 can be made, according to a first embodiment, by means of an iris or inductive diaphragm comprising two metal septums (also referred to by reference numerals 4) arranged symmetrically in respect to a median longitudinal plane, which develops parallel to an axis z of the radiation propagation. Themetal septums 4 of the first inductive diaphragm identify a first coupling radiation opening 24 of the electromagnetic field. - With reference to the equivalent electric scheme of
FIG. 2 , the firstinductive diaphragm 4 is represented as an optimal shunt inductor having an inductive impedance jX4. The walls of the firstinductive diaphragm 4 have the same height as the height b offilter 100. - The first resonator segment of the
waveguide 5 has a length, taken on the axis z, approximately equal to half of length of the central wave of the filter: λg0/2 and it is coupled to theinput 3 by theinductive diaphragm 4. Theresonator segment 5 can also have a length which is multiple of the value λg0/2. - Moreover, the
first resonator segment 5 is coupled to asecond resonator segment 7 by a firstresonant coupling 6. The first resonant coupling device is a resonant coupling structure which introduces a discontinuity configured to introduce a zero in the transmission frequency response of the band-pass filter 100. - In more detail, the first
resonant coupling device 6 is configured to resonate at a frequency equal to the value of the frequency of the zero being introduced in the transmitting response of the band-pass filter 100. In particular, such a transmission zero concurs to increase the selectivity of the filter in the higher and lower stop-bands of thefilter 100 itself. - For different frequencies from the resonance frequency of the first
resonant coupling device 6, the device itself behaves as a coupler. The position on the frequency axis of the transmitting zero can be determined by synthesis procedures known to those skilled in the art. The transmission zero corresponds, in a practical implementation of thefilter 100, to an attenuation peak. - As it is visible in the example of
FIG. 1 , the firstresonant coupling device 6 can be made by at least a body within the waveguide of thefilter 100 and having a reduced height relative to height b of the waveguide itself. In particular, the firstresonant coupling device 6 comprises two parallelepiped-shaped (for example, with a square base) posts, parallel oriented to axis y, arranged, for example, symmetrically relative to the median longitudinal plane and having a height h lower than dimension b. - Such first reduced-
height posts 6 are schematically depicted inFIG. 2 as a shunt-arranged resonant circuit element and therefore as a series of an inductor and a capacitor with a total reactance X6 (with impedance jX6). Such an impedance jX6 results in the presence of a zero at the frequency fz1 in the transmission response of the band-pass filter 100. - Even if the first reduced-
height posts 6 play a role as a resonant body, they act for different frequencies from the resonance frequency as a coupling device which, in conjunction with thefirst diaphragm 4, causes thefirst guide segment 5 to be a resonant cavity. - The
second resonator segment 7, with a length equal to approximately half of the central wavelength of the filter (i.e. λg0/2) has an end (opposite the first posts 6) connected to a second inductivediscontinuity coupling device 8. Such acoupling device 8 is analogous to thefirst device 4 and comprises a second inductive diaphragm which identifies asecond opening 9 for radiating. - In the
equivalent scheme 110 inFIG. 2 , the second inductivediscontinuity coupling device 8 is represented by another inductive shunt impedance jX8. - The band-
pass filter 100 further comprises athird resonator segment 10 with a length approximately equal to λg0/2, coupled to thesecond resonator segment 7 by the secondinductive diaphragm 8. - According to the concerned example, the
third resonator segment 10 is connected to a third inductive discontinuity coupling device 11 (analogous to the first coupling device 4), implemented by a further inductive diaphragm (impedance jX11) provided with athird aperture 12. - The
third resonator segment 10 is further coupled to a fourth resonator segment 13 (of a length λg0/2) connected to a secondresonator coupling device 14, comprising two second reduced-height posts, and analogous to thefirst coupling device 6 and having an impedance jX14. - The second reduced-
height posts 14 are such to resonate, for example, at a different resonance frequency fz2 and therefore they cause the presence of another zero in the transmitting frequency response of the band-pass filter 100, at the frequency fz2. For example, the zero placed at frequency fz1 increases the selectivity in the lower stop-band, while the zero at frequency fz2 increases the selectivity of the higher stop-band at the pass-band B of thefilter 100. For different frequencies from the resonance frequency fz2 the second posts with a reducedheight 14 act as a coupling device. - The
fourth resonator segment 13 is coupled to a fifth resonator segment 15 (approximately λg0/2 long) by the second posts with a reducedheight 14. The fifthresonant segment 15 is then coupled to anoutput 17 of thefilter 100 by a fourth inductivediscontinuity coupling device 18 implemented by a respective fourth inductive diaphragm having afourth opening 19 and an inductive impedance jX18. - According to the examples illustrated, the
output 17 of thefilter 100 is the waveguide segment which has anoutput opening 25 for providing the filtered signal and for being coupled to a load or to a further waveguide segment or to a further filter. It is to be observed that theresonant coupling devices filter 100 guide wherein the electric field has is at the minimum, in order not to degrade the figure of merit of theresonator guide segments - Dimensioning and Operation of the Filter
- The dimensioning of the first, second, third and fourth
inductive diaphragm height posts filter 100. This causes the first, the second, the third, the fourth and thefifth guide segments filter 100. - Even though in
FIG. 1 only five resonant cavities are shown, the band-pass filter 100 may comprise a number N of cavities, equal to the filter order. In general, thefilter 100 may comprise a plurality of resonant coupling structures in generally located (analogous tostructures 6 and 14), in order to introduce in the band-pass response up to N+1 transmission zeros for a N-order filter. - The frequency value fz1 of the first zero (e.g, lower than the mid-band frequency f0 of the filter 100) and the frequency value fz2 of the second zero (e.g, higher than the mid-band frequency f0 of the filter 100) may be suitably selected in the stop-bands within the whole operative band of the waveguide, i.e. from the cut-off frequency fc up to the value 2fc and beyond.
-
FIG. 3 a shows an example of the firstresonant coupling device 6, in the case of an individual square-base, reduced-height post with a side d and a height h, arranged so that it is centred in respect to the transversal cross-section of the waveguide where it is inserted.FIG. 3 b shows the circuit equivalent to the first reduced-height post 6, comprising an impedance jX6 parallel between two segments of the transmission line having length θ6, to which the following parameters are associated: - X6 is the equivalent reactance of the reduced-
height post 6; - Zo is, the characteristic impedance of two segments of the transmission line;
- θ6 is the equivalent electric length of the two segments of transmission line;
- To is the position of the reference sections in respect to which the equivalent circuit is defined.
- The equivalent reactance X6 and the electric length θ6 are related to the transmission parameters of the first reduced-
height post 6 according to the following relations: -
- wherein S11 is the reflectance and S21 is the transmittance, both evaluated in respect to the To sections.
- For example, taking into account a guide having a=30 mm and b=a/2, the frequency dependence on the ratio X6/Z0 (normalised reactance) for the first reduced-
height post 6 ofFIG. 3 a, was diagrammatically depicted inFIG. 4 for several values of height h=9, 11, 13 and 15 mm (side d=3 mm). For each value of h, the behaviour of the normalized reactance of the first reduced-height post 6 corresponds to a LC-series resonator around its own resonance frequency. Such a resonance frequency decreases when height h increases. - Considering the same dimensional values, exemplarily denoted above, the frequency dependence of the equivalent length θ6 is diagrammatically depicted in
FIG. 5 , where both reference sections are arranged at the longitudinal symmetry plan of the first reduced-height post 6 (To inFIG. 3 a). As it is seen inFIG. 5 , the behaviour of the equivalent electric length θ6 is analogous to the one of a full-height post having an inductive behaviour; the slope of the electric length θ6 increases upon the increase of height h. -
FIG. 6 shows the frequency dependence of the ratio X6/Z0 for several values of the side d=2, 3, 4 and 5 mm (height h=13 mm). However the resonance frequency and the behaviour of the ratio X6/Z0 with the frequency depend on both the height h and on the side d. This behaviour allows to use the reduced-height post 6 as a coupler between waveguide resonators and allows also the introduction of transmission zero. - By properly dimensioning the components of the band-pass filter 100 a transmission response may be obtained by the filter which is, for example, of the Chebyshev type, with transmission zeros (pseudo-elliptical response). Due to the presence of zeros, thus the band-pass filter selectivity can be increased (i.e. the attenuation in the higher and lower stop-bands at the pass-band) with the same number of resonators.
-
FIG. 7 illustrates the behaviour of transmittance S21 and reflectance experimentally measured on a band-pass filter analogous to that inFIG. 1 , schematically depicted inFIG. 2 , implemented with a waveguide and having two transmission zeros (corresponding in the practice to attenuation peaks). The experiments were carried out on a filter made by the Applicant in a R70/WR137 guide, having inner dimensions equal to 34.85 mm×15.799 mm, using silvered aluminium. The project was carried out according to the following specifications - a central frequency f0=7.070 GHz;
- a bandwidth B=28 MHz;
- a level of the band return loss of 22 dB;
- order N=5;
- two transmission zeros (corresponding in practice to attenuation peaks) located at frequencies fz1=7.020 GHz (in the lowest stop-band) and fz2=7.120 GHz (in the highest stop-band).
- The experimental results shown in
FIG. 7 (solid lines) perfectly match those provided by the simulation (dashed lines). - As to the operation, an electromagnetic wave in the form of, the mode TE10 (basic mode in a rectangular guide) affects the
input 3. The electromagnetic wave propagates along the axis z of thefilter 100, being partially reflected at theinput 3 and partially transmitted at theoutput 17, according to the frequency of the wave itself. - When passing through the
filter 100 the electromagnetic wave with a frequency comprised within the pass-band B of the filter itself interacts with the resonances of theresonant segments coupling devices output 17 with a reduced reflection at theinput 3. The electromagnetic wave with a frequency outside the pass-band of thefilter 100, instead, undergoes reflections within the filter and therefore it is substantially stopped, to an extent which depends on the difference between the wave frequency and the filter central frequency. - The electromagnetic wave having a frequency equal to one of the resonance frequencies of the two
resonant coupling devices output 17, giving rise to an attenuation peak) as the effect of the short-circuit created along the guide by the resonant coupling devices. - It is to be observed that according to other embodiments, each of the inductive diaphragms described above may be made not by the pairs of
symmetrical septums FIG. 1 , but by the following alternative modes: - an asymmetrical inductive iris, comprising an individual full-height septum 50 (
FIG. 8 a); - a full-height inductive post 51 (
FIG. 8 b): the post may be centred, or not, have a rectangular, circular or other base; there can be one or more full-height inductive posts 51. - Moreover, instead of an inductive diaphragm, an asymmetrical capacitive iris can be used as a (non-resonant) coupling device, comprising a reduced-height, full-width septum 52 (
FIG. 8 c). Also a symmetrical capacitive iris may be used, comprising another reduced-height, full-width septum. - Moreover, each of the
resonant coupling devices FIG. 1 , by one or more full-height posts having different forms (for example, with a rectangular, square, circular or other base). For example,FIG. 9 a shows an individual reduced-height post 53 with a square plan, whileFIG. 9 b shows a pair of reduced-height posts - It is to be observed that the illustrated geometries are only exemplary; and also a pair of reduced-height posts may be used wherein one is secured to the top wall of the
filter 100 guide and the other is secured to the bottom wall of the same guide, or wherein the post are differently shaped and sized in respect to each other. -
FIG. 10 shows a first embodiment of the filter ofFIG. 1 comprising awaveguide 200 provided with atop wall 21 facing abottom wall 22 and afirst side wall 23, facing asecond side wall 27. In the Figures, the same reference numerals refer to the same or analogous components or devices. - The
waveguide 200 ofFIG. 10 can be obtained by processing an individual metal slug (corresponding to the bottom of thewaveguide 200, which comprises the bottom wall 22), for example, by milling steps (which can be carried out by Numeric Controlled machines) which allow, by removing the material, to form the bodies which form the inductive/capacitive or resonant discontinuities present in thewaveguide 200. The rounding offs within thewaveguide 200, shown as a way of example inFIG. 10 , refer to the particular use of a candle-mill. -
FIG. 11 illustrates an analogous embodiment to that ofFIG. 10 , which requires, however, two slugs, one for thetop wall 21 integral with the reduced-height posts guide 200, integral with thebottom wall 22. The embodiment ofFIG. 11 has an advantage, in respect to that ofFIG. 10 , in terms of manufacturing process when the distances between the reduced-height posts side walls -
FIG. 12 refers to anotherembodiment 300 of the “metal insert-type” band-pass filter 100, which is an alternative to those ofFIGS. 10 and 11 . InFIG. 12 , the metal-insert type band-pass filter 300 is made by assembling (for example by welding or the like) afirst guide shell 31, astructure 32 and asecond guide shell 33, all made of metal. The first and thesecond guide shells - The
structure 32, intended to be placed in the middle of the wave guide and parallel to the axis of propagation z comprises a carrying longitudinal toplaminar rod 34 and a carrying longitudinal bottomlaminar rod 35, between which a plurality of laminar discontinuity bodies extend. - In particular, the
structure 32 comprises a first reduced-heightlaminar body 36, a first full-heightlaminar body 37, a second reduced-heightlaminar body 38, a second full-heightlaminar body 39 and a third reduced-heightlaminar body 40. - The operation and the equivalent electric scheme of the filter in
FIG. 12 are analogous to those disclosed above and therefore the full-heightlaminar bodies laminar bodies - The four guide segments interposed between consecutive
laminar bodies plate 32, may be used, each one having the plurality of discontinuities indicated above, which will be arranged, preferably, symmetrically in respect to a longitudinal middle plane of the assembled waveguide. - The embodiment shown in
FIG. 12 is particularly advantageous since it provides a simple and quite inexpensive manufacturing method based on working theplate 32, which provides removing metal portions, for example, by laser cutting or electro-erosion. - The metal-insert band-
pass filter 300 of FIG. 12 is a four-resonator filter with three transmission zeros.FIG. 13 shows the behaviours of the reflectance S11 and the transmittance S21 obtained by numerical simulation, referring to an example of themetal insert filter 300 ofFIG. 12 with a guide dimension of 30×15 mm; pass-band 7.50-7.75 GHz, returnlosses 20 dB, three zeros at the following frequencies: 7 GHz, 8.25 GHz and 9 GHz. - As it is evident to those skilled in the art, the alternating inductive coupling devices in respect to the resonant coupling devices may follow a different order from those disclosed and designated as a way of example in the accompanying Figures. Furthermore, it is to be noted that according to a variant of the
filter 300 ofFIG. 12 , instead of metal lamina 32 a thin metallised dielectric plate may be used, from the processing thereof the above disclosed coupling devices being obtained (“E-plane filters” technique). -
FIG. 14 refers to anembodiment 400 of the band-pass filter 100, which may be implemented by processing the low-loss dielectric slug, and suitable for the guided propagation of electromagnetic waves, obtaining hollow geometrical shapes which reproduce as a negative both the shape of the inductive coupling devices such as thediaphragms - These cavities obtained in the dielectric slug are then coated with a metal material by a metallization step, which enables to obtain the four external walls of the waveguide of the
dielectric filter 400. In particular, the dielectric-type filter 400 ofFIG. 14 is a four-resonator band-pass filter with a transmission zero. For the sake of clarity of the depiction inFIG. 14 , they are not shown. -
FIG. 15 shows the behaviours of the reflectance S11 and transmittance S21 obtained by a numerical simulation with reference to an example of thedielectric filter 400 ofFIG. 14 , made of quartz, of 15×7.5 mm; pass-band 7.5-8.00 GHz, returnloss 20 dB, a zero at 8.85 GHz. - The band-
pass filter 100 and its different embodiments disclosed above, with reference to the several appended figures, may further comprise adjusting screws (not shown since they are known to those skilled in the art) which allow to carry out a fine calibration by compensating possible process tolerances. - The band-
pass filter 100 may be used in waveguides which operate at the typical microwave frequencies, for example at frequencies ranging from 100 MHz and 40 GHz. - The disclosed band-pass filter is advantageous since it allows to obtain a remarkable increase in the selectivity in respect to the prior art filters, with the same number of resonators, and at the same time it may be implemented quite simply, with similar size and losses, and according to the different technologies currently available. A particular advantage is due to the possibility to implement also the resonant coupling devices by bodies within the guide itself.
- Finally, the present invention is capable of a number of modifications and variants, all of which fall within the appended claims, whereas the technical details can change according to specific needs.
Claims (16)
Applications Claiming Priority (1)
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PCT/IT2010/000306 WO2012004818A1 (en) | 2010-07-09 | 2010-07-09 | Waveguide band-pass filter with pseudo-elliptic response |
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US20130154772A1 true US20130154772A1 (en) | 2013-06-20 |
US8981880B2 US8981880B2 (en) | 2015-03-17 |
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US13/809,109 Expired - Fee Related US8981880B2 (en) | 2010-07-09 | 2010-07-09 | Waveguide band-pass filter with pseudo-elliptic response |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2016186296A1 (en) * | 2015-05-21 | 2016-11-24 | 주식회사 케이엠더블유 | Waveguide filter |
JP2017153158A (en) * | 2007-06-27 | 2017-08-31 | レゾナント インコーポレイテッドResonant Inc. | Low-loss variable radio frequency filter |
US20180034125A1 (en) * | 2015-03-01 | 2018-02-01 | Telefonaktiebolaget Lm Ericsson (Publ) | Waveguide E-Plane Filter |
CN109713412A (en) * | 2018-12-20 | 2019-05-03 | 常州机电职业技术学院 | A kind of tunable face the E cutting face H waveguide bandpass filter and its design method |
CN114824707A (en) * | 2022-04-28 | 2022-07-29 | 西南科技大学 | 5G millimeter wave reconfigurable waveguide filter and passband adjusting method thereof |
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MX341059B (en) * | 2012-09-07 | 2016-08-05 | Nec Corp | Band-pass filter. |
CN102856615A (en) * | 2012-09-14 | 2013-01-02 | 电子科技大学 | Waveguide band-pass filter suitable for 380-390 GHz frequency range |
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Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6118978A (en) * | 1998-04-28 | 2000-09-12 | Hughes Electronics Corporation | Transverse-electric mode filters and methods |
US20070262834A1 (en) * | 2006-05-11 | 2007-11-15 | Seiko Epson Corporation | Bandpass filter, electronic device including said bandpass filter, and method of producing a bandpass filter |
US20070272557A1 (en) * | 2006-05-23 | 2007-11-29 | Mehlin Dean Matthews | System and method for isotope separation |
US20100180437A1 (en) * | 2005-10-21 | 2010-07-22 | Mckinzie Iii William E | Systems and methods for electromagnetic noise suppression using hybrid electromagnetic bandgap structures |
US8067997B2 (en) * | 2005-11-10 | 2011-11-29 | The Arizona Board Of Regents On Behalf Of The University Of Arizona | Apparatus and method of selecting components for a reconfigurable impedance match circuit |
US8604982B2 (en) * | 2006-08-25 | 2013-12-10 | Tyco Electronics Services Gmbh | Antenna structures |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0202247D0 (en) | 2002-01-31 | 2002-03-20 | Quasar Microwave Tech | Electromagnetic filter assemblies |
FR2848342A1 (en) | 2002-12-09 | 2004-06-11 | Thomson Licensing Sa | Pass-band filter with pseudo-elliptical response of wave guide type has floating insert inside one inductive iris |
DE102005047336A1 (en) | 2005-09-30 | 2007-04-12 | Ericsson Ab | Waveguide band stop filter |
ITRM20080307A1 (en) | 2008-06-12 | 2009-12-13 | Rf Microtech S R L | FILTER WAVING GUIDE. |
-
2010
- 2010-07-09 US US13/809,109 patent/US8981880B2/en not_active Expired - Fee Related
- 2010-07-09 EP EP10747692.1A patent/EP2591524A1/en not_active Withdrawn
- 2010-07-09 WO PCT/IT2010/000306 patent/WO2012004818A1/en active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6118978A (en) * | 1998-04-28 | 2000-09-12 | Hughes Electronics Corporation | Transverse-electric mode filters and methods |
US20100180437A1 (en) * | 2005-10-21 | 2010-07-22 | Mckinzie Iii William E | Systems and methods for electromagnetic noise suppression using hybrid electromagnetic bandgap structures |
US8595924B2 (en) * | 2005-10-21 | 2013-12-03 | William E. McKinzie, III | Method of electromagnetic noise suppression devices using hybrid electromagnetic bandgap structures |
US8067997B2 (en) * | 2005-11-10 | 2011-11-29 | The Arizona Board Of Regents On Behalf Of The University Of Arizona | Apparatus and method of selecting components for a reconfigurable impedance match circuit |
US20070262834A1 (en) * | 2006-05-11 | 2007-11-15 | Seiko Epson Corporation | Bandpass filter, electronic device including said bandpass filter, and method of producing a bandpass filter |
US20070272557A1 (en) * | 2006-05-23 | 2007-11-29 | Mehlin Dean Matthews | System and method for isotope separation |
US20110079516A1 (en) * | 2006-05-23 | 2011-04-07 | Mehlin Dean Matthews | System and method for isotope separation |
US8604982B2 (en) * | 2006-08-25 | 2013-12-10 | Tyco Electronics Services Gmbh | Antenna structures |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017153158A (en) * | 2007-06-27 | 2017-08-31 | レゾナント インコーポレイテッドResonant Inc. | Low-loss variable radio frequency filter |
US20180034125A1 (en) * | 2015-03-01 | 2018-02-01 | Telefonaktiebolaget Lm Ericsson (Publ) | Waveguide E-Plane Filter |
US9899716B1 (en) * | 2015-03-01 | 2018-02-20 | Telefonaktiebolaget Lm Ericsson (Publ) | Waveguide E-plane filter |
WO2016186296A1 (en) * | 2015-05-21 | 2016-11-24 | 주식회사 케이엠더블유 | Waveguide filter |
CN107925144A (en) * | 2015-05-21 | 2018-04-17 | 株式会社Kmw | Waveguide pipe wave filter |
US10530028B2 (en) | 2015-05-21 | 2020-01-07 | Kmw Inc. | Waveguide filter formed by a casing and a cap fitted into the casing, where a tuning sheet is interposed between the cap and the casing |
CN109713412A (en) * | 2018-12-20 | 2019-05-03 | 常州机电职业技术学院 | A kind of tunable face the E cutting face H waveguide bandpass filter and its design method |
CN114824707A (en) * | 2022-04-28 | 2022-07-29 | 西南科技大学 | 5G millimeter wave reconfigurable waveguide filter and passband adjusting method thereof |
CN116995385A (en) * | 2023-09-25 | 2023-11-03 | 电子科技大学 | Double zero configuration structure for improving out-of-band performance of terahertz waveguide filter |
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US8981880B2 (en) | 2015-03-17 |
EP2591524A1 (en) | 2013-05-15 |
WO2012004818A1 (en) | 2012-01-12 |
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